Method of making crowns and forms therefor



T. C. HANSEN METHOD OF MAKING CR OWNS AND FORMS THEREFOR Filed April 61922 Elm 00mm T. Q. HANSEN.

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THOMAS C. HANSEN, 0F CAREY, KANSAS.

"METHOD OF MAKING CROWNS AND FORMS THEREFOR.

Application filed April 6, 1922. Serial no. 550,154.

To all whom it may concern:

Be it known that I, THOMAS C. HANSEN, a citizen of the United States,residing at (Janey, in the county of Montgomery and State of Kansas,have invented certain new vide a process whereby the gold band which isusually fitted around the prepared root may. be welded to the topportion of the crown. Another object of the invention is to improvegenerally the process by which the crown pattern is prepared before thecasting -operation takes place.

Other objects and advantages of the invention will be apparent from thefollowing description when taken in connection with the accompanyingdrawing, in which:

Fi re 1 is a side elevation of a toothfor whic a crown is to bemade.

. Figure 2 is asimilar view with a gold band fitted thereto.

Figure 3 is a perspective view of a hydrocarbon form to be used in theprocess.

Figure 4 is a sectional view through the band and hydrocarbon form.

Figure 5 is a sectional view, showing the completed pattern after themolding material has been formed into the mold.

- Fi re 6 is a view similar to Figure 5, showing the mold after the samehas been heated.

Figure 7 is a sectional view through the completed crown, and

Figure 8 shows the crown applied to the tooth.

Referring to the drawing more in detail, the numeral 1 designates atooth which has been prepared for a crown. After being thus prepared, a36 gauge, 24 carat band 2 is fitted over the prepared root in ordertoget a proper adaptation therefor without causing irritation to thegums. A form 3, of celluloid or similar material, is then fitted overthe tooth and secured to the band 2 by castmg wax, as indicated, at I. a

These forms are to be made in a number of shapes and sizes, both withand without cusps, to conform as nearly as possible to the configurationof the normal teeth, but, of course, will not suit every case. In orderto get the exact configuration desired, or in order to strengthen aparticular part of the crown, or for the purpose of perfecting theocelusal surface casting wax may beadded to the form 3 at anypoint'desired, as indicated by the numeral 5. It should also be statedthat the celluloid forms are made relatively thin and are, therefore,flexible to such degree that their shape may be changed somewhat whenbeing fitted to the band 2.

The pattern before being placed in the mold may have a portion ofcasting wax 6 or a liningapplied on the interior thereof, in order toprovide suflicient thickness at the top of the crown.

A pin 7 is then inserted into the pattern and the latter is lifted fromthe prepared root and inserted in a mold. The molding material 8 is thenpoured into the mold and allowed to harden, as indicated in Figure 5.The mold is then heated, thus volatilizing the casting wax and celluloidform; the gases escaping through the passage 9 made by the pin 7 Themolten gold or other casting material is now forced into the moldthrough the passage 9 and welds itself to the band 2 and otherwise takesthe shape of the mold vwill have a definite seat on the tooth and willnot permit a variation'to, defeat the requirewithout departin from thespirit of the invention; all such aim to include in the scope of theappended claims.

What I claim as new and desire to secure by Letters Patent is:

1. An article to be used in preparing crowns, comprising a hollo vs formof combustible material of substantially the exterior configuration ofthe normal tooth.

2. An article to be used in preparing crowns comprising a hollowcelluloid form of substantially the exterior configuration of the normaltooth.

3. A process of forming patterns for crowns including fitting a band tothe prepared root, and securing a hollow form of substantially the shapeof the tooth to be crowned to the band.

4. A process of forming patterns for crowns including fitting a metalband to the prepared root, and applying a hollow form of volatilematerial of substantially the shape of the tooth tobe crowned to theband by castin wax.

5. process of forming patterns for crowns including fitting a. metalband-to the prepared root, applying a hollow form of substantially theshape of the tooth to be crowned, shaping the lower edge of the form tothe band, and securing the band and form together by casting wax.

6. A process of forming patterns for crowns comprising fitting a metalband around the prepared root, applying a hollow form of volatilematerial of substantially the shape of the tooth to be crowned, shapingthe lower edge of the form to the band, securing the band and formtogether by casting wax, and addin casting wax to the form at otherpoints deslred.

7. A process of formin crowns for teeth including fitting a metalllcband to the prepared root, applyin a hollow form of volatile material tothe band, inserting the pattern thus formed in a mold, pouring in themolding material, heating the mold to volatilize the hollow form, andfilling the mold cavity with material to form the crown.

THOMAS C. HANSEN.

